I used to get asked by friends far more than I do now, about how to start blogging. I think these days blogging tools are so much easier, familiar and there are so many resources out there, that people are able to just get up and running more easily.
But if you are still thinking about starting, or wanting to develop an existing blog, do take a look at Pro Blogger's latest resources, 'ProBlogger’s Guide to your First Week of Blogging'. Like everything Darren Rowse puts out, it looks very helpful. And do check out his '31 days to build a better blog'.